Thanks for your inquiry and the opportunity at earning your business. Actually the link you sent is for the older style 3 balde propellers. In general you need to drop a full pitch for every 150-200 rpm so for 800 rpm you would need to drop about 4 pitches. You have to purchase the 4 blade front propellers as a full set, nit just the front though. Using the link below you can add your selected product(s) to your shopping cart and the shipping estimator located at the bottom of the shopping cart page will give you a shipping cost based on your specific postal code. Let me know if you need any further technical information or help placing your order. In either case I will be glad to assist!